JP3201921B2 - Method for producing aliphatic polyisocyanate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aliphatic polyisocyanate by reacting an aliphatic polyamine or a hydrochloride or carbonate thereof with phosgene.

[0002] Aliphatic polyisocyanates are extremely useful compounds as raw materials for polyurethane-based materials, polyurea-based materials, and polyisocyanurate-based materials in the fields of chemical industry, resin industry, paint industry and the like.

[0003]

2. Description of the Related Art An aliphatic polyisocyanate is produced by a phosgene method by directly reacting an amine with phosgene to obtain an isocyanate, or by temporarily reacting an amine with hydrochloric acid gas or carbon dioxide gas to obtain an amine hydrochloride or carbonate. The method is roughly divided into the salt formation method of obtaining an amine salt of the above and reacting it with phosgene.In each case, an aliphatic polyisocyanate is produced by producing an intermediate carbamoyl chloride and dehydrochlorinating it. How to

[0004] The reaction for dehydrochlorinating carbamoyl chloride to isocyanate requires a low reaction rate, and generally requires a high temperature of at least 120 ° C or higher, usually 130 ° C or higher. The reason for this slow reaction rate is that the reaction itself is low, but the other factor is that
This reaction is an equilibrium reaction. That is, the reason is that hydrochloric acid gas generated by the decomposition of carbamoyl chloride reacts with isocyanate that has already been generated to generate carbamoyl chloride again. In the production of isocyanate by the phosgene method, for the above-mentioned reason, 130 ° C.
The reaction must be carried out at such a high temperature for a very long time, and the produced isocyanate is exposed to heat for a long time to cause tarification of the isocyanate itself, thereby lowering the yield. In addition, carbamoyl chloride as an intermediate has a far higher taration rate than isocyanate and further reduces the yield,
There was a problem that the yield was extremely poor.

[0005] As a method for solving the above-mentioned problem, the rate of carbamoyl chloride production from amine is increased by charging phosgene in excess, and at the same time, hydrochloric acid remaining in the reaction system is also removed from the reaction system by excess phosgene. A method has been devised for producing an aliphatic polyisocyanate while always shifting the equilibrium toward the isocyanate side by removing the polyisocyanate. According to this method, the concentration of carbamoyl chloride during the phosgenation reaction is reduced, and the rate of production of the aliphatic polyisocyanate is also improved, so that the reaction is completed in a short time. To get the product.

Therefore, this improved method is used for the production of aliphatic polyisocyanates by the phosgene method. Specifically, usually at least 120 ° C. or higher, or 130 ° C.
The reaction is carried out by heating to above ℃ and charging phosgene in excess. Further, a method has been reported in which by-products are suppressed by using an ester solvent to obtain an isocyanate with a high yield (JP-A-3-7253 and JP-A-3-204851).

However, even if the aliphatic polyisocyanate is produced by these methods, it is difficult to suppress tar formation, and usually tar formation occurs at about 10%, and in some cases, tar formation occurs. Decrease. In addition, excess phosgene becomes a complete loss and requires detoxification treatment,
Furthermore, the production of a large amount of tar imposes a great burden on the tar processing operation and processing step, leading to deterioration in operability and increase in processing cost. Therefore, it was hard to say that the method was still economically satisfactory.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a high-yield, economical process for producing an aliphatic polyisocyanate by the phosgene method.

In view of such a situation, the present inventors have intensively studied a method for producing an aliphatic polyisocyanate by the phosgene method. As a result, surprisingly, if an inert gas is charged into the reaction system, The present inventors have found that improvements such as reduction in the amount of phosgene used, prevention of tar formation, improvement in yield, and the like have been made, and the present invention has been achieved.

That is, the present invention is characterized in that, when an aliphatic polyamine or its hydrochloride or carbonate is reacted with phosgene in an inert liquid medium, the reaction is carried out while charging an inert gas into the reaction system. Is a method for producing an aliphatic polyisocyanate.

The aliphatic polyamine used in the present invention includes a bifunctional or more functional organic amine compound in which an amino group is not directly bonded to an aromatic ring, and examples thereof include the following compounds.
Pentamethylenediamine, hexamethylenediamine,
2,2,4-trimethylhexamethylenediamine, 2,
Linear aliphatic polyamines such as 4,4-trimethylhexamethylenediamine, octamethylenediamine, nonamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, isophoronediamine, bis (4-aminocyclohexyl) methane, 2, 2-bis (4-aminocyclohexyl) propane, m-xylylenediamine, p-xylylenediamine, o-xylylenediamine, or a mixture thereof arbitrarily, such as xylylenediamine, bis (aminomethyl) norbornene. Examples thereof include cyclic aliphatic polyamines, amino acid polyamines such as lysine methyl ester and lysine aminoethyl ester.

The isocyanates obtained from these aliphatic polyamines are called aliphatic polyisocyanates.

In the process according to the invention, these aliphatic polyamines can be used in free form or in hydrochloride or carbonate form.

That is, in the method of the present invention, phosgene is reacted with an aliphatic polyamine or a salt thereof mixed in a reaction liquid medium while charging an inert gas, that is, the inert gas is introduced into the phosgenation reaction system. A major feature is that the reaction is performed while charging. Therefore, it is possible to react with phosgene while charging an inert gas, using a free aliphatic polyamine as a raw material, or to react with phosgene while charging an inert gas, using a salt of an aliphatic polyamine as a raw material. .

The inert gas used in the present invention is a gas that does not react with aliphatic polyisocyanate, phosgene, hydrochloric acid and the like, and examples thereof include nitrogen, helium, neon, and argon. As long as an inert gas is used, any of the gases produces excellent effects, but nitrogen is preferred from the viewpoint of economy.

The charging rate of the inert gas charged into the reaction system cannot be limited because it depends on the reaction conditions and the equipment conditions, but if it is limited, the charging rate of the phosgene charged is limited. Is preferably at least 0.2 times by volume, more preferably at least 0.5 times by volume.

In the present invention, the raw materials and the reaction solution are
In order to easily produce an aliphatic polyisocyanate by smoothly mixing, stirring, and transferring a liquid, it is preferable to use a reaction liquid medium.

The reaction liquid medium used in the present invention is an inert solvent which does not react with aliphatic polyamines, aliphatic polyisocyanates, phosgene, hydrochloric acid and the like. Specific examples include benzene, toluene, mixed xylene, o-xylene, m-xylene, p-xylene, cumene, 2,2,5
Hydrocarbons such as trimethylhexane, decane, ethylcyclohexane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, o
Halogenated hydrocarbons such as dibromobenzene, nitrogen-containing compounds such as nitrobenzene, N, N-dimethylformamide, N, N-dimethylacetamide, N, N′-dimethylimidazolidinone, dibutyl ether, ethylene glycol dimethyl ether ; Ethers such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, anisole, phenetole, methoxytoluene, benzyl ether, diphenyl ether, ketones such as heptanone and diisobutyl ketone, amyl formate, acetic acid-n
-Amyl, isoamyl acetate, methyl isoamyl acetate, -n-butyl acetate, isobutyl acetate, 2-ethylbutyl acetate, methoxybutyl acetate, ethoxyethyl acetate, methoxyethyl acetate, methoxypropyl acetate, ethyl acetate,
Secondary hexyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, benzyl acetate, phenyl acetate, methyl carbitol acetate, ethylene glycol diatate, ethyl propionate, n-butyl propionate, isoamyl propionate, butyric acid Esters such as ethyl, butyl butyrate, isoamyl butyrate, butyl stearate, butyl lactate, amyl lactate, dimethyl phthalate, methyl benzoate, ethyl benzoate and the like can be mentioned.

Further, among these inert liquid media,
In order to ensure a satisfactory reaction rate at normal pressure, which does not require large equipment costs, an inert liquid medium having a boiling point of 130 ° C. or higher is preferable. Esters are preferred because they have an effect of suppressing the generation of a by-product called a chloro form in which a part or all of the isocyanate group is substituted with a chlorine atom.

The amount of the inert liquid medium used in the reaction is as follows:
It is preferably 3 to 40 times by weight, more preferably 4 to 20 times by weight, relative to the raw material aliphatic polyamine or its salt. 3
Although it is not impossible even if the weight is less than the weight, mixing and stirring may be difficult in some cases. If it exceeds 40 times by weight, the volumetric efficiency will deteriorate, and it will not be industrially advantageous.

The kind of the inert liquid medium may be used alone or as a mixture of two or more kinds, but one kind is preferable from the viewpoint of recovery and reuse.

The reaction mode in the present invention is a method in which a free aliphatic polyamine is used as a raw material, and the reaction is carried out with phosgene while charging an inert gas in an inert liquid medium.
Using a free aliphatic polyamine as a raw material, the salt is formed by reacting with hydrochloric acid gas or carbon dioxide gas in an inert liquid medium, and then reacting with phosgene while charging the salt-forming mass with an inert gas. There is a way to make it happen.

In the above method, the reaction is usually carried out in an inert liquid medium by the following two-step reaction. In the first stage, the internal temperature is 0 to
While maintaining the temperature at 100 ° C., phosgene is charged, and the reaction is carried out at a low temperature. If it exceeds 100 ° C., the yield tends to decrease, which is not preferable. If the temperature is lower than 100 ° C., a sufficient effect can be achieved, but if the temperature is lower than 0 ° C., an excessively large refrigeration facility is required, so that it is not an industrially advantageous method. In addition, the reaction on the low-temperature side is such that the raw material aliphatic polyamine simultaneously reacts with the functional group (amino group /
When charged at a rate ratio of 0.2 to 1.5 (COCl ₂ ) molar ratio, favorable results are often obtained. The second stage is 1
The temperature is increased from the stage, and while the internal temperature is maintained at 120 to 200 ° C., preferably 130 to 200 ° C., charging of the inert gas is also started in addition to the already charged phosgene, and at the high temperature side, Is performed. If the temperature is lower than 120 ° C., the reaction rate tends to be slow, which is not very practical. If the temperature is higher than 200 ° C., the yield tends to decrease due to tarification, which is not preferable. Further, even if the charging of the inert gas is started from the reaction on the low temperature side, there is no problem.

In the above method, first, an aliphatic polyamine is reacted with hydrochloric acid gas or carbon dioxide gas in an inert liquid medium to produce a salt of the aliphatic polyamine. The internal temperature during the salt formation reaction is preferably 0 to 30C. If it exceeds this, the reaction time of the next phosgenation reaction tends to increase, which is not preferable. If the temperature is lower than 0 ° C., an excessively large refrigeration facility is required as described above, and this is not an industrially advantageous method. In this salt formation reaction, similarly to the reaction on the low temperature side, the raw material aliphatic polyamine is simultaneously added to the hydrochloric acid gas at a functional group (amino group / HCl) molar ratio of 0.
Charges at speed ratios of 2 to 1.5 often give favorable results. Next, after raising the temperature, phosgene is reacted while charging an inert gas into the salt-forming mass. The internal temperature is I
As in the reaction on the high temperature side, the temperature is preferably 120 to 200 ° C, more preferably 130 to 200 ° C.

In the present invention, the reaction can be carried out under reduced pressure, under atmospheric pressure, or under a pressure higher than atmospheric pressure. In each of the above methods, after completion of the reaction, unreacted phosgene and hydrochloric acid are purged with an inert gas, the solvent is removed, and the product is distilled and purified to take out the aliphatic polyisocyanate.

[0026]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Example 1 Reflux cooler, thermometer, raw material gas (hydrochloric acid gas, carbon dioxide gas)
Blow pipe, inert gas blow pipe, liquid material dropper,
1000 g of trichlorobenzene (boiling point 210 ° C.) was placed in a 3 l reaction flask equipped with a liquid medium dropper and a stirring blade, and m-xylylenediamine (hereinafter referred to as m-XD) was placed in a liquid material dropper.
Abbreviated as A. ) 136.2 g (1.0 mol) and 945 g of the remaining trichlorobenzene were charged into a liquid medium dropper. Here, the total amount of the liquid medium used was 14.3 times the weight of m-XDA. Next, while stirring and cooling, hydrochloric acid gas was supplied from the raw material gas injection pipe at a rate of 36.5 g / H (1 mol / H), and m-XDA and trichlorobenzene of the dropper were simultaneously mixed at a constant ratio of 1: 6.9. The dropping was started at the same time as the charging of hydrochloric acid gas at a rate of 540.6 g / H while negotiating at a weight ratio, and was completed over 2 hours (m-XDA).
The rate ratio between the hydrogen gas and the hydrochloric acid gas is amino group / HCl = 1). Further, aging was performed for 0.5 hour while charging hydrochloric acid gas as it was. These series of salt formation reactions were performed at 10 ° C. next,
After the salt-forming mass was heated to 160 ° C., phosgene gas was blown in at a rate of 250 g / H (2.52 mol / H) from the raw gas blowing pipe, and at the same time, 23 l of nitrogen gas was blown from the inert gas blowing pipe. / H, the internal temperature was raised to 190 ° C over 1 hour,
While maintaining at 90 ° C., until the reaction solution becomes almost transparent,
The reaction was continued for 3.0 hours. Next, unreacted phosgene and hydrochloric acid are purged with nitrogen gas, unreacted m-XDA hydrochloride 0.2 (as dry) is removed by filtration, and the filtrate is desolvated and distilled under reduced pressure (1-2 mmHg). And m-chlorobenzyl isocyanate (hereinafter abbreviated as m-CBi).
185.3 g of m-xylylene diisoananate (hereinafter abbreviated as m-XDi) containing 2% by weight (yield in terms of pure content = 9)
6.3%). The results are also shown in Table 1.

Comparative Example 1 Example 1 was carried out without charging nitrogen as an inert gas.
The reaction was carried out in the same manner as in Example 1 and the removal was carried out in the same manner as in Example 1. The unreacted m-XDA hydrochloride filtered off was 0.1 g (as dry). Other results,
It is shown in Table 1.

[0028]

[Table 1] The introduction of nitrogen gas reduced the use of phosgene and improved the yield.

Example 2 The same reaction apparatus as in Example 1 was used. 800 g of ethoxypropyl acetate (boiling point: 158 ° C.) was charged to a 2 l reaction flask, 136.2 g (1.0 mol) of m-XDA was charged to a liquid material dropper, and 400 g of the remaining ethoxypropyl acetate was charged to a liquid medium dropper. The total amount of liquid medium used is m-XD
The weight was 9 times the weight of A. Then, while stirring and cooling,
Hydrochloric acid gas was supplied at 36.5 g / H (1
Mol / H), the m-XDA and ethoxypropyl acetate of the dropper were dropped at the same time at a constant weight ratio of 1: 2.9, and simultaneously with the charging of hydrochloric acid gas at a rate of 268.1 g / H. And finished over 2 hours (mX
The rate ratio between DA and hydrochloric acid gas is amino group / HCl = 1).
Further, aging was performed for 0.5 hour while charging hydrochloric acid gas as it was. These series of salt formation reactions were performed at 20 to 60 ° C. Next, after raising the temperature of the salt-forming mass to 135 ° C., 33 g / H of phosgene gas was supplied from a raw material gas injection pipe.
(0.33 mol / H), and at the same time, nitrogen gas was blown at a rate of 15 l / H from an inert gas injection pipe, and the reaction was continued while the internal temperature was maintained at 135 to 140 ° C. After 17 hours, the reaction was completed when the reaction solution became almost transparent. Next, unreacted phosgene and hydrochloric acid were purged with nitrogen gas, and unreacted m-XDA hydrochloride 1.2
After removing (as dry) by filtration, the filtrate was desolvated and distilled under reduced pressure (1-2 mmHg) to give 171.0 g of m-XDi containing 0.7% by weight of m-CBi (yield in terms of pure content = 9).
0.2%).

[0030] Using the reaction device of Example -3 Example -2 liquid medium (abbreviated as ODCB less. Boiling point 180 ° C.) from ethoxypropyl acetate o- di-chloro benzene in the same manner as in Example -2 change Preparation was performed. Next, while vigorously stirring and cooling, m-XDA and ODCB of the dropper were simultaneously mixed at a constant weight ratio of 1: 2.9 with phosgene gas at a rate of 100 g / H from the raw material gas injection pipe at a rate of 178.7 g / h. At the rate of H, the dropwise addition was started at the same time as the charging of the phosgene gas, and was completed over 3 hours (the rate ratio between m-XDA and phosgene was amino group / COCl ₂ = 0.65). These series of reactions are 0
Performed at ３０30 ° C. Next, the reaction mass was gradually reduced to 135.
After the temperature was raised to 200 ° C., phosgene gas was blown at a rate of 20 g / H (0.2 mol / H), nitrogen gas was blown at a rate of 23 l / H from an inert gas blowing pipe, and the internal temperature was raised to 13 ° C.
The reaction was continued while maintaining the temperature at 5 to 140 ° C. After 8 hours, the reaction was completed when the reaction solution became almost transparent. Next, unreacted phosgene and hydrochloric acid are purged with nitrogen gas, and 0.3 (as dry) of insoluble matter is removed by filtration. The filtrate is desolvated and distilled under reduced pressure (1-2 mmHg) to give m-C
168.6 g of m-XDi containing 4.2% by weight of Bi
(Yield in terms of pure content = 85.8%).

Example 4 Using the apparatus of Example 2, the liquid medium was changed from ethoxypropyl acetate to isoamyl acetate (boiling point 142 ° C.)
Except that the hydrochloric acid gas was changed to the carbon dioxide gas, the procedure up to the salt formation reaction was performed in exactly the same manner as in Example-2. Next, after the salt-forming mass was heated to 100 ° C., phosgene gas was blown at a rate of 33 g / H (0.33 mol / H) from the raw material gas blowing tube, and simultaneously, nitrogen gas was blown from the inert gas blowing tube. Was blown at the same rate of 15 l / H as in Example 2, and while maintaining the internal temperature at 100 to 105 ° C., 8 hours and 13
The temperature was raised to 5 ° C, and the reaction was further continued while maintaining the internal temperature at 135 to 140 ° C. Ten hours after the temperature was raised to 135 ° C., the reaction was terminated when the reaction liquid became almost transparent. Next, the reaction solution was treated in the same manner as in Example-2. 0.5 g (as dr) of unreacted m-XDA carbonate filtered off
y). Table 2 shows the results.

Comparative Example 2 The reaction was carried out in the same manner as in Example 4 except that nitrogen gas as an inert gas was not blown during the phosgenation reaction.
Processed. The unreacted m-XDA carbonate filtered off was 0.4
g (as dry). Table 2 shows the results.

[0033]

[Table 2] The introduction of nitrogen gas also improved the yield in the carbonate method.

Examples 5 to 8 and Comparative Example 3 The effect of charging an inert gas was examined. The reaction and treatment were carried out in the same manner as in Example 2 except that the liquid medium was changed to ethoxyethyl acetate (boiling point: 156 ° C.), and the charging rate of nitrogen was changed. Table 3 shows the results. The filter cake is unreacted m-XDA hydrochloride.

[0035]

[Table 3] The yield improved almost in proportion to the amount of nitrogen gas blown.

Examples -9 to 12 and Comparative Examples -4 to 7 The effects of charging an inert gas were examined by changing the liquid medium. The reaction and treatment were carried out in the same manner as in Example 2 except that the liquid medium was changed. Table 4 shows the results.

[0037]

[Table 4] ODCB; o-dichlorobenzene (boiling point 180 ° C) Mixed xylene (boiling point 138 to 144 ° C) Anisole (boiling point 154 ° C) MPA; methoxypropyl acetate (boiling point 158 ° C) The same was recognized even if it was changed.

Examples 13 to 14 and Comparative Examples -8 to 9 The effect of charging an inert gas with the two-stage cooling and heating method of Example 3 was examined. The reaction and treatment were carried out in the same manner except that the charging rates of nitrogen and phosgene on the liquid medium and the high temperature side were changed. Table 5 shows the results.

[0039]

[Table 5] In the direct method of directly reacting an amine with phosgene, the yield was improved and the amount of phosgene was reduced by charging nitrogen gas regardless of the type of the inert liquid medium, similarly to the hydrochloride method.

Examples 15 to 21 and Comparative Examples 10 to 16 In the salt formation method of Example 2, the aliphatic polyamine was changed,
The effect of inert gas charging was studied. The reaction and treatment were conducted in the same manner as in Example 2 except that the aliphatic polyamine was changed. The reaction was performed until the reaction solution became almost transparent. Table 6 shows the results.

[0041]

[Table 6] For aliphatic polyisocyanates other than XDi, the yield was improved by charging nitrogen gas.

Examples 22 to 23 and Comparative Examples -17 to 18 The effect of charging an inert gas was examined by replacing m-XDA with HMDA by the two-stage cooling / heating method of Example-3. The charge rates of nitrogen and phosgene on the hot side were changed,
Processed. Table 7 shows the results.

[0043]

[Table 7] HMDi, an aliphatic polyisocyanate other than XDi
Even when was produced by the direct method, the yield was improved and the amount of phosgene was reduced by charging nitrogen gas.

Example-24, Comparative Example-19 The effect of charging an inert gas was examined. The reaction and treatment were carried out in the same manner as in Example 2 except that the liquid medium was changed to isoamyl acetate (boiling point: 142 ° C.), the blowing rate of phosgene was changed to 25 g / H, and the charging rate of nitrogen was changed to 10 l / H. Table 8 shows the results.

[0045]

[Table 8] The effect of charging nitrogen gas was recognized, and the yield was improved.

[0046]

According to the present invention, the desired aliphatic polyisocyanate can be easily and efficiently produced in a high yield, with a reduced amount of phosgene, and is therefore extremely valuable as an industrial production method.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-192205 (JP, A) JP-A-63-280050 (JP, A) JP-A-3-204851 (JP, A) JP-A-3-20805 7253 (JP, A) JP-A-1-151548 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 263/10 C07C 265/14

Claims (5)

(57) [Claims] 1. An aliphatic polyamine or a hydrochloride or carbonate thereof and a phosgene which are reacted in an inert liquid medium while introducing an inert gas into the reaction system. A method for producing a polyisocyanate. 2. The method according to claim 1, wherein the inert gas is nitrogen. 3. The method of claim 1, wherein the aliphatic polyamine is xylylenediamine,
Hexamethylenediamine, trimethylhexamethylenediamine, isophoronediamine, bis (aminocyclohexyl) methane, 2,2-bis (aminocyclohexyl)
The method according to claim 1, wherein the method is selected from the group consisting of propane, bis (aminomethyl) cyclohexane, and bis (aminomethyl) norbornene. 4. The method according to claim 1, wherein the reaction is carried out in an inert liquid medium having a boiling point of 130 ° C. or higher. 5. The method according to claim 4, wherein the inert liquid medium is an ester.